JP2741870B2 - Call setup method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a call setting system, and more particularly, to a high-speed setting method of a return path of a call setting system.

[Conventional technology]

For the conventional call setup method in packet switching, the user interface is CCITTRED BOOK X.25,
The in-network procedure is also shown in X.75. The outline is described in “Packet Switching Technology and Its Application” edited by IEICE.
It is described on pages 102 to 105. According to the above "packet switching technology and its application", in X.25 which is a user interface, when a call is set up between packet terminals (PTs) via a packet network, the calling PT sends a call request packet to the call request packet. Put the free call number of your PT and send it to the starting communication station. When this is transferred to the destination communication station in the packet network, the destination communication station searches for a free call number of the destination PT, sets this call number in a destination packet, and sends it to the destination PT. At the receiving PT, the call receiving packet is returned to the destination communication station, and the starting communication station
Returns a connection completion packet to the calling PT. Thereafter, communication between PTs becomes possible. On the other hand, since the intra-network procedure X.75 is also based on X.25, the above-described procedure between PTs is executed between communication stations.

As described above, in the conventional call setting, a call in both directions can be established by a response (an incoming call reception packet and a connection completion packet) to a call setting request (an outgoing call packet and an incoming call packet). The outward route and the return route are the same route. The same value is used for the call number of the outward route between the PT and the station or between the stations.

[Problems to be solved by the invention]

The above prior art has a problem that independent paths cannot be assigned to the forward path and the return path at the time of call setting, and independent call numbers cannot be assigned to the round-trip call numbers between the terminal and the station or between the stations.

In multimedia exchange over a broadband network, it is effective to use a fixed-length mini-packet frame relay system based on out-of-band call control. In this case, generally, round-trip call numbers are determined independently. Further, when considering the data transfer system, the usage rate of a specific route in a specific direction may increase. In such a situation, when only the same route can be selected for the forward route and the return route, it often occurs that the call setting on the other route is unsuccessful due to the inability to use one route.

Furthermore, when the call numbers of the round-trip between stations are the same, in a situation where a call from another route is output to the same route, the call setting often ends unsuccessfully due to the collision of the two call numbers. I do.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a call setting method capable of assigning independent paths to the forward path and the return path when setting up a call, and assigning an independent call number to a round-trip call number between a terminal and a station or between stations. Is to provide.

[Means for solving the problem]

The above-mentioned object is to provide a method in which, when the round-trip route is set independently, the communication destination station sends a path independent of the first call path to the communication start station in accordance with the first call setting request on the outward path from the communication start station. In the second call setup, each station sequentially assigns an independent call number, and when the same route is used as a round trip route, the inter-station This is achieved by setting both the outgoing call number and the newly set return call number to be responded to when the response is returned.

[Action]

According to the present invention, by writing the call endpoint address in the call setting request information and decoding it at the communication destination station,
It is possible to set up a call in the communication station. Further, the communication destination station does not need to change the procedure of the conventional destination terminal or the destination subscriber network for transmitting the second call setup request in accordance with the reception of the first call setup request.

Therefore, according to the call setting method according to the present invention, the present invention is also applied as an inter-LAN communication procedure employing connectionless communication without setting a call. Also, by using both the second call setting request and the response to the first call setting request, the setting can be completed in the same time as when the conventional method is adopted.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is an overall configuration diagram of a network system to which the present invention is applied, in which a plurality of LANs 2a, 2b, 2c, and 2d are connected to a communication station.
They are interconnected by a connection network consisting of 1a, 1b, 1c, 1d and transmission lines 5a, 5b, 5c, 5d, 5e. In addition, each of the above communication stations,
Although it is possible to directly accommodate telephones, data terminals, and the like, the type of accommodation is not essential for the present invention, and is omitted here for simplicity.

Here, the flow of data on the network will be described, taking as an example a case where the terminal 4a accommodated in the LAN 2a communicates with the terminal 4c accommodated in the LAN 2c via the LAN node 3a.

When the terminal 4a is the data transmission source, the transmission data is LAN
It is sent to the LAN 2a via the node 3a. The communication station 1a becomes a communication activation station, and takes in data received from the LAN when the data is not addressed to a terminal in the same LAN. Then, from the received data and the database in the communication station,
It recognizes that it is destined for the terminal 4c accommodated in the LAN 2c, and specifies a communication route to reach the LAN 2c. Based on this, relay information is notified to the communication stations 1b and 1c, which are relay routes, a response to the notification is obtained from the communication destination station, and a route is established. Then, data received from the LAN 2a is transmitted to this route. After receiving the data, the communication destination station 1c transfers the data to the LAN terminal 4c.

Next, the communication protocol of the communication station will be described with reference to FIG. Each layer corresponds to the OSI reference model of ISO. The layer structure L4a is a protocol configuration on the LAN terminal 4a, and is the same as the layer structure L4c in the LAN terminal 4c. The layer structure L4a includes a physical layer 4aA, a MAC layer 4aB, and an upper layer 4aC.

In the drawing, thick lines 351 and 353 indicate the flow of data, and thin lines 352 indicate the flow of call control information such as the establishment of a route between communication stations.

Data 351 generated by the LAN terminal 4a is transmitted to the LAN-side layer structure L1a of the communication station 1a via the layer structure L3a of the LAN node 3a.
Reach Here, the lower two layers of the layer structures L3a and L1a are:
It is the same as the lower two layers 4aA and 4aB of the layer structure L4a. Communication station
1a checks the MAC destination address of the received data in the MAC layer 1aB, and recognizes that the received data is inter-LAN transfer data. In this case, the communication station 1a, the call activation layer
In 1aC, after specifying the route with reference to the in-station database (call established), the call setting layer 311
It outputs call control information 352 including path information indicating the above-described route and a call number valid between communication stations. The communication station 1b receives the call setting information 325 at the call setting layer 312, creates a database (relay table) necessary for relaying subsequent data, assigns a new call number, and sends the new call number to the next-stage communication station 1c. Relay. 313 is a call setting layer of the communication station 1c, and the call setting layers 311 to 313 are structurally the same.

On the other hand, the communication station 1a transmits the call control information 352, and after receiving a response to the call control information from the communication station 1c, transfers the data received from the LAN to the communication station 1b. This data transfer is
This is performed by the data transfer layer D1a. Layer structure D1b, D
1c is a transfer layer in each of the communication stations 1b and 1c, which have the same structure. The communication station 1b transfers the received transfer data 353 to the communication station 1c according to the relay table in the call setting layer 312. The communication station 1c transfers the data to the LAN 2c. The lower two layers of the layer structures L1c, L3C and L4c are the same as the lower two layers 4aA and 4aB of the layer structure L4a.

FIG. 1A shows a first embodiment of the communication procedure according to the present invention.

The communication station 1a receives the data 10 from the LAN 2a and transmits the call setting information 12a to the communication station 1b. After processing this, the communication station 1b returns a first response 13a, and transmits the call setting information 12b to the communication station 1b.
Relay to 1c. The communication station 1c sends a first response 13b to the communication station 1b.
Is returned, the second response 14 is transferred to the communication station 1a via the communication station 1b. Note that this second response 14
The contents are not changed in 1b. Further, call-back (return) call setting information 15b is transmitted, which can be selected independently of the outward route.
The figure shows a case in which the route via the communication station 1d is passed because the route is in a congested state. Hereinafter, the procedure of 15a, 15b, 16a, 16b, and 19 started by the communication station 1c is the same as the series of steps started by the communication station 1a.

The communication station 1a receives the response 14 from the communication station 1c,
The transfer of the data 17 is started to the communication station 1b. On the other hand, when the communication station 1c receives the data 20 from the LAN terminal 4c to the LAN terminal 4a, the communication station 1c can wait for the response 19 without transmitting a new call and transmit it.

FIG. 1 (b) shows a communication procedure in the case where the second response and return call setting information are used as the second embodiment of the present invention. FIG. 1 (b) shows the call setting and combined response 30a, 30
b serves both as the second response 14 in FIG. 1 (a) and the return call setting information 15a, 15b. The other steps have the same meaning as in FIG. 1 (a). Therefore, the first responses 16a and 16b in FIG.
This is a response regarding the call setting information.

FIG. 1 (c) shows that there is no return call setting information,
A third embodiment of the present invention is shown in which bidirectional call setup is established in response to a call. In FIG. 1C, the same meaning as in FIG. 1A is shown, except for the first responses 40a and 40b. The first responses 40a and 40b indicate acceptance of the call having the call number given by 12a and 12b, respectively, and indicate a return path between the communication stations 1a and 1b and between the communication stations 1b and 1c. Has a function of newly assigning a call number. Therefore, as described in detail below, the first responses 40a and 40b include
Both the call number requested from the preceding communication station and the call number for return communication are described.

FIG. 4 shows the transfer format of the call control information and subsequent data. 60 shows the overall format, which is a fixed length of 36 Bytes,
When the call setting information 352 is transferred, the call setting numbers are set in the call number (M) 50a and the call number (L) 50b, and the user area 5 is set.
3 takes the form shown in the call setting information 53b. At the time of data transfer, the call number (M) 50a and the call number (L) 50b are set with the call number given by the call setting, and the information 53a is set in the user area 53. The control information 51 includes call number error detection information, priority information, and the like. The division number 52 is used when transferring data longer than 31 bytes, and sets information indicating the position of the block divided into 31 bytes with respect to the data before division.

The call control salary 53b includes a protocol identifier 54a indicating a protocol in accordance with the following format, a control target call number (M) 54b, (L) 54c which is a target for call setting and release, and a message type shown in FIG. It comprises a message type 54d, additional information 54e, and an FCS 54f for detecting errors from the protocol identifier 54a to the additional information 54e. In addition, additional information
54e is composed of an information element identifier 55, information contents 57, and an information element length 56 indicating the length.

FIG. 5 shows the relationship between the message type, the information element in that case, and the information element length. In the call setting message 61, path information including a 1-byte / communication station address string of the communication station is essential. n indicates a cascade connection means of the communication station. In the call setup message, to perform call back setup,
The source LAN address (DA) and the destination LAN address (SA) are transferred as the terminal address of the call. In this example, the LAN address length is the maximum length 6 determined by the IEEE802 committee.
Byte is adopted.

The call release message 62 notifies a cause of release such as a buffer overflow, a shortage of call numbers, or a hardware failure.

In the first call setup and release response (first response) message 63, the return call number is notified to independently set the return call number. This information element is not required,
When this element is not set, the call number of the call setting request is used for the round-trip signal as in the past.

In the second call setup and release response (second response) message 64, there is no information element to be transferred.

The call setup and response message 65 requires information elements of both the above-described call setup message and the second call setup and release response message.

The notification message 66 is a message for notifying control information between arbitrary communication stations, and is used, for example, for updating a database in the communication station and collecting log information. For this,
1Byte / transmission / reception communication station address of the communication station is required as an information element. In the communication message, a block identifier in the communication station indicating a table type or the like to be notified, a command indicating processing contents, and control data are further transmitted.

 FIGS. 6A and 6B show block diagrams of communication stations.

The information 210 from the LAN is checked by the LAN access unit 101 for the FCS and the frame length, and if the frame is a normal frame, it is taken into the reception buffer 104. The received data is transmitted to the selection control unit 102
Thus, it is determined using the selection table 103 whether or not the transfer is between LANs. In the case of intra-LAN transfer data, the subsequent data is erased from the reception buffer by overwriting the same position in the reception buffer.

The processor 107 checks the presence or absence of the call setting for the data in the reception buffer 104 using the setting call table 106. If the setting has been completed, the data transfer is immediately performed using the call information in the set call table. In this case, the receive buffer
Data is read from 104 to the division buffer 108, and a header 110 is created / registered based on the call information, and the division number setting unit 109 is reset. Data is divided into 31 bytes and sent. On the other hand, if the call has not been set up,
After extracting the route information from 105 and registering it in the setup call table, a call setup message is sent to the line 150 as call control information. The multiplexing unit 111 multiplexes the call control information and the data, and transmits this information 152 to the corresponding port 121 of the switch 112.
Send to

When this is call control information, the port input information 152 is output to the port 119 as indicated by a broken line 153. In the case of data, as indicated by a broken line 156, according to the contents of the relay table 113,
The output is output to an output port 118 connected to the transmission path 5a via the link transmission unit 116. A processor 114 is connected to the port 119. The processor sets or cancels call information in the relay table 113 based on the call control message and the structure table 115. After processing the call control information, the processor 114 relays to the next stage using the dedicated port 120. This dedicated port 120 is also used for a notification message transfer 155 between the two processors 107 and 114.

On the other hand, the input information 157 from the transmission line 5a is
Input from 17 to port 123. If this information is relay data, it is exchanged with the relay destination port 131 (arrow 158), if it is call control information, it is exchanged with port 119 (arrow 159), and if it is data destined for LAN2a, it is exchanged with port 122 (arrow 160). .

The received data 161 includes 51 in the control information described with reference to FIG.
Under the control of the composition control unit 125, based on the detection result of the final detection unit 124 that detects the final data identifier in the divided data, and the call number 50a, b, the call is sorted by call SW126. Are stored in the assembly buffer 128. The call information assembling buffer 127 is dedicated to call control information.

The data assembled in the LAN format is sent to the transmission buffer 130 after the order of the division numbers is checked by the division number check unit 129, and is transmitted to the LAN after obtaining the transmission right of the LAN access unit 101. .

Note that, among the messages in FIG. 5, the call setup / release, the second response, the combined call setup response, and the notification are activated by the processor A. The processor 114 processes these messages, and relays and activates the first response.

FIG. 7 shows the table type and the content information length in the station.
The selection table 103 stores the terminal addresses in the LAN accommodated by the communication station. Only when there is no address in this table that matches the DA of the received LAN data, transmission processing is performed assuming that the data is transfer data between LANs.

The routing table 105 includes a LAN other than the target LAN, that is, a LAN terminal address in the LAN 2b, 2c, 2d as viewed from the LAN 2a, an output port identifier within the own station arriving at the LAN terminal, a communication relay station address string, and a communication destination. Station address,
And an output port identifier. Note that a communication relay station output port identifier string may be directly specified instead of the communication relay station address string. In this case, a structure table described later is unnecessary.

The set call table 106 is a table for storing set call information, and includes a source and destination LAN terminal addresses, which are call endpoint addresses, a given call number, and an output port identifier.

The contents of the relay table 113 are registered when a call is set, and are deleted when the call is released. In this table, the relationship between the input call number, the output call number, and the output port identifier is described for each input port.

The structure table 115 stores an address of an adjacent communication station and an identifier of an output port leading to this station.

According to this embodiment, since the return path is set in advance at the communication destination station, the return data transfer delay from the LAN can be significantly reduced. For example, if the distance between LAN terminals 4a and 4c is
At 5000 km, 50 msec round-trip propagation delay required for call setup
Therefore, a total of 70 msec, that is, a delay of 5 msec in the communication relay station and a response processing time of 15 msec in the communication destination station can be reduced.

〔The invention's effect〕

According to the present invention, the destination communication station responds to the start communication station from the start communication station by requesting the start communication station to return the second call on the return path that is independent of the path of the first call. A request for setting is made, and at the time of the second call setting, each station sequentially assigns an independent individual number. If the same route is used as a round-trip route as before, when a response is returned between the stations, the response target Since both the outgoing call number and the newly set return call number can be set, the usage rate of the specific route is high, and one way of the round trip is not available, or due to collision of the call number, There is no unsuccessful call setup. Therefore, the throughput and the delay performance in the communication station can be improved.

[Brief description of the drawings]

1 (a) to 1 (c) are diagrams for explaining an example of a call control communication procedure of the present invention, FIG. 2 is a block diagram showing an example of a network system to which the present invention is applied, and FIG. FIG. 4 is a diagram showing a protocol configuration in the system of FIG. 2, FIG. 4 is a diagram showing a frame structure of call setting information and data, FIG. 5 is a diagram for explaining message types, and FIG.
FIG. 7B is a block diagram showing the configuration of the communication station, and FIG. 7 is a diagram showing the contents of various tables provided in the communication station. DESCRIPTION OF SYMBOLS 1 ... Communication station, 2 ... LAN, 15 ... Second call setup message, 30 ... Call setup and use response message, 40 ... First response message.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-159942 (JP, A) JP-A-64-20756 (JP, A) JP-A-63-181549 (JP, A) JP-A-63-181549 280539 (JP, A) IEICE Technical Report, SS E88-74

Claims (5)

(57) [Claims] 1. A call setting method wherein a first call setting request is issued from a communication starting station to a communication destination station prior to information transfer, and a response to the call setting request is returned from the communication destination station to the communication starting station. The communication destination station receiving the first call setting request may be a destination terminal or a destination subscriber network connected to the communication destination station, and a source terminal of information connected to the communication activation station. Alternatively, a call setup request for forming a path independent of the first call using the transmission source subscriber network as a receiving side is transmitted to the communication starting station. method. 2. The call according to claim 1, wherein the communication destination station transmits a response signal to the first call setup request and the second call setup request as an integrated signal. Setting method. 3. A first return path identical to the first call setup path is formed by a response signal to the first call setup request returned from the communication destination station to a communication start station, 2. The call setting method according to claim 1, wherein a second return path is formed by the call setting request of No. 2 and one of them is used as an active system and the other is used as a standby system. 4. A communication control station issues a first call setting request to a communication destination station prior to information transfer, and each communication relay station interposed between the communication activation station and the communication destination station transmits the first call setup request to the communication destination station. The call setup request is sequentially relayed to another subsequent communication relay station or the above-mentioned communication destination station, and a first response is returned to the previous-stage communication starting station or another communication relay station, and the above-mentioned communication destination station In the call setting method for returning a second response to the communication starting station, each communication relay station receiving the first call setting request transmits a first response from the preceding communication station in the first response. A call setting method wherein a requested call number and a call number for return communication are returned. 5. A plurality of LANs, which are subscriber networks, are connected via a relay network composed of a plurality of communication stations, and a communication starting station that has received inter-LAN transfer data from the LAN is connected to a communication destination station. Determines whether a call has been set up.If the call has been set up, apply the already assigned call number to transfer the LAN-to-LAN transfer data to the relay network.If no call has been set up, route to the destination LAN. Sends a call setup request containing information indicating the above to the relay network, waits for a response from the communication destination station, and after receiving the response, applies the call number given to the route between the LANs. A call setting method in a network configured to transfer transfer data to a relay network, wherein the call setting request sent from the communication starting station is transmitted to the LAN.
Including a MAC address pair indicating the source and destination of the inter-transfer data, the communication destination station stores the MAC address pair received by the call setting request in a setting call table,
A call setting method, wherein a call setting request for a return path is transmitted to the communication starting station.